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115 lines
3.7 KiB
Rust
115 lines
3.7 KiB
Rust
// Vendored from https://github.com/matklad/always-assert/commit/4cf564eea6fcf18b30c3c3483a611004dc03afbb
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//! Recoverable assertions, inspired by [the use of `assert()` in
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//! SQLite](https://www.sqlite.org/assert.html).
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//!
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//! `never!` and `always!` return the actual value of the condition if
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//! `debug_assertions` are disabled.
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//!
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//! Use them when terminating on assertion failure is worse than continuing.
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//!
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//! One example would be a critical application like a database:
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//!
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//! ```ignore
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//! use stdx::never;
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//!
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//! fn apply_transaction(&mut self, tx: Transaction) -> Result<(), TransactionAborted> {
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//! let delta = self.compute_delta(&tx);
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//!
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//! if never!(!self.check_internal_invariant(&delta)) {
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//! // Ok, something in this transaction messed up our internal state.
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//! // This really shouldn't be happening, and this signifies a bug.
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//! // Luckily, we can recover by just rejecting the transaction.
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//! return abort_transaction(tx);
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//! }
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//! self.commit(delta);
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//! Ok(())
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//! }
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//! ```
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//!
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//! Another example is assertions about non-critical functionality in usual apps
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//!
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//! ```ignore
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//! use stdx::never;
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//!
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//! let english_message = "super app installed!"
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//! let mut local_message = localize(english_message);
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//! if never!(local_message.is_empty(), "missing localization for {}", english_message) {
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//! // We localized all the messages but this one slipper through the cracks?
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//! // Better to show the english one then than to fail outright;
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//! local_message = english_message;
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//! }
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//! println!("{}", local_message);
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//! ```
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/// Asserts that the condition is always true and returns its actual value.
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///
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/// If the condition is true does nothing and and evaluates to true.
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///
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/// If the condition is false:
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/// * panics if `force` feature or `debug_assertions` are enabled,
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/// * logs an error if the `tracing` feature is enabled,
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/// * evaluates to false.
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///
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/// Accepts `format!` style arguments.
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#[macro_export]
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macro_rules! always {
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($cond:expr) => {
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$crate::always!($cond, "assertion failed: {}", stringify!($cond))
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};
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($cond:expr, $fmt:literal $($arg:tt)*) => {{
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let cond = $cond;
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if cfg!(debug_assertions) || $crate::assert::__FORCE {
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assert!(cond, $fmt $($arg)*);
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}
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if !cond {
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$crate::assert::__tracing_error!($fmt $($arg)*);
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}
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cond
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}};
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}
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/// Asserts that the condition is never true and returns its actual value.
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///
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/// If the condition is false does nothing and and evaluates to false.
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///
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/// If the condition is true:
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/// * panics if `force` feature or `debug_assertions` are enabled,
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/// * logs an error if the `tracing` feature is enabled,
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/// * evaluates to true.
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///
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/// Accepts `format!` style arguments.
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///
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/// Empty condition is equivalent to false:
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///
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/// ```ignore
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/// never!("oups") ~= unreachable!("oups")
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/// ```
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#[macro_export]
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macro_rules! never {
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(true $($tt:tt)*) => { $crate::never!((true) $($tt)*) };
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(false $($tt:tt)*) => { $crate::never!((false) $($tt)*) };
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() => { $crate::never!("assertion failed: entered unreachable code") };
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($fmt:literal $(, $($arg:tt)*)?) => {{
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if cfg!(debug_assertions) || $crate::assert::__FORCE {
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unreachable!($fmt $(, $($arg)*)?);
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}
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$crate::assert::__tracing_error!($fmt $(, $($arg)*)?);
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}};
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($cond:expr) => {{
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let cond = !$crate::always!(!$cond);
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cond
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}};
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($cond:expr, $fmt:literal $($arg:tt)*) => {{
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let cond = !$crate::always!(!$cond, $fmt $($arg)*);
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cond
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}};
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}
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#[doc(hidden)]
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pub use tracing::error as __tracing_error;
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#[doc(hidden)]
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pub const __FORCE: bool = cfg!(feature = "force-always-assert");
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